#include <iostream>

using namespace std;
struct R
{
    int n;
    struct R *next;
};
struct R *create(int n)
{
     struct R *head=NULL,*p1=NULL,*p2=NULL;
     int i;
     for(i=1;i<=n;i++)
     {  p1=(struct DATA *)malloc(sizeof(R));
        scanf("%ld",&p1->num);
        p1->next=NULL;
        if(i==1) head=p1;
        else p2->next=p1;
        p2=p1;
      }
      return(head);
int main()
{
    cout << "Hello world!" << endl;
    return 0;
}
